Controlled release encapsulated hypochlorite deactivator for use in denture cleansers

Abstract

A denture cleansing composition of the hypochlorite type is rendered substantially free of hypochlorite chlorine odor by incorporating into the composition a hypochlorite deactivator. The deactivator is released into the cleansing solution at a controlled rate to optimize cleansing efficacy at a reduced hypochlorite/chlorine odor. The deactivators suitable for use in this invention include sodium perborate monohydrate and sodium nitrite. The preferred method of controlling deactivator release rate is by encapsulating the deactivator.

What is claimed is: 
     
       1. A controlled release encapsulated hypochlorite deactivator composition comprising: (a) a hypochlorite deactivator having a particle size of about 20 mesh to about 50 mesh; and   (b) a coating composition completely surrounding and enclosing the deactivator said coating composition comprising: (1) a water insoluble, pH insensitive film forming composition wherein said film forming composition is ethylcellulose, and   (2) a plasticizer in an amount from about 18% to about 40% by weight based on the total weight of the coating composition wherein the coating composition comprises about 6% to about 20% (w/w) of the encapsulated deactivator.     
     
     
       2. The deactivator composition according to claim 1 wherein the hypochlorite deactivator is an alkali metal perborate, alkali metal nitrite, or ascorbic acid. 
     
     
       3. The composition according to claim 2 wherein the alkali metal is sodium. 
     
     
       4. The composition according to claim 2 wherein the film forming composition is ethylcellulose, the alkali metal is sodium, the plasticizer is dibutyl sebacate, and the coating composition comprises 18% (w/w) of the encapsulated deactivator. 
     
     
       5. A process for preparing a controlled release encapsulated hypochlorite deactivator which comprises: (a) encapsulating the deactivator in a coating composition comprising a water permeable insoluble film forming composition wherein the film former is ethylcellulose and a plasticizer for the film forming composition said coating comprising about 6% to about 20% by weight of the encapsulated deactivator, based on the weight of deactivator, and said coating comprising about 18% to about 40% by weight of plasticizer based on the total weight of the coating composition; and   (b) curing the encapsulated deactivator for about 45 minutes to about 75 minutes at a curing temperature of about 85° C. to about 100° C.   
     
     
       6. The process according to claim 5 wherein the film former is ethylcellulose and the plasticizer is dibutyl sebacate. 
     
     
       7. The process according to claim 5 wherein the plasticizer comprises about 20% to about 30% (w/w) of the coating. 
     
     
       8. The process according to claim 5 wherein the coating comprises about 18% by weight of the encapsulated deactivator based on the weight of deactivator. 
     
     
       9. The process according to claim 5 wherein the coating is applied by a fluidized bed spray coating process from a solution or emulsion of the coating composition. 
     
     
       10. The process according to claim 9 wherein the coating composition comprises about 6% solids to about 30% by weight of the solution or emulsion. 
     
     
       11. The process according to claim 10 wherein the coating emulsion comprises: (a) about 50% by weight of an ethylcellulose emulsion having a solids content of about 30% (w/w), based on the coating emulsion; and   (b) about 3% by weight based on the coating emulsion of dibutyl sebacate.   
     
     
       12. The process according to claim 5 wherein the hypochlorite deactivator has a particle size range of about 20 mesh to about 50 mesh. 
     
     
       13. The process according to claim 5 wherein the hypochlorite deactivator is an alkali metal perborate, alkali metal nitrite, or ascorbic acid. 
     
     
       14. The process according to claim 13 wherein the deactivator is NaNO 2 .